DIELECTRIC AND CONDUCTIVITY RELAXATION IN SODIUM CARBOXYMETHYL CELLULOSE AND ITS ACID FORM

We report a study on the dielectric relaxation behaviour of samples of sodium carboxymethyl cellulose and its acid form covering the frequen cy range 20-10(5) Hz and the temperature range 40-90 degrees C. Treati ng the data in terms of an impedance formalism using the electrical mo dulus rather than admittance formalism using the complex dielectric co nstant revealed that two relaxation processes in NaCMC while its acid form, HCMC, shows only one. The high frequency process in both NaCMC a nd HCMC is attributed to the reorientation of the carboxymethyl groups . These results suggest that the previous assumption of lacton formati om in HCMC seems to be untenable. The lower frequency in NaCMC is due to a conductivity relaxation. The shorter relaxation time of the latte r indicates that the transport of charge carrier requries the motion o f the chain segment. The effect of the degree of substitution on the d ipolar relaxation in NaCMC is also discussed. Copyright (C) 1996 Publi shed by Elsevier Science Ltd.